Bug 106838

Summary:	Improve error message when trying to connect in degraded environment with sms only
Product:	ModemManager	Reporter:	Michael Scherer <misc>
Component:	general	Assignee:	ModemManager bug user <modemmanager>
Status:	RESOLVED FIXED	QA Contact:
Severity:	minor
Priority:	medium
Version:	1.6
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Michael Scherer 2018-06-06 12:13:11 UTC

So today, I tried to connect to the 4G network while in a tunnel (Paris public transportation). Usually, that work fine but it seems my provider suffered some outage that did result in a rather unhelpful message:

juin 06 13:01:47 windgrace.example.org ModemManager[870]: <warn>  error parsing unsolicited registration: Could not parse the registration status response

I restarted with debug and got the following traces:

<debug> Modem not yet registered in a 3GPP network... will recheck soon
<debug> Running registration checks (CS: 'yes', PS: 'yes', EPS: 'yes')
<debug> (ttyUSB2) device open count is 2 (open)
<debug> (ttyUSB2): --> 'AT+CREG?<CR>'
<debug> (ttyUSB2): <-- '<CR><LF>+CREG: 2,6<CR><LF><CR><LF>OK<CR><LF>'
<warn>  error parsing unsolicited registration: Could not parse the registration status response
<debug> (ttyUSB2) device open count is 3 (open)
<debug> (ttyUSB2) device open count is 2 (close)

It seems that 2,6 mean 

" 6 registered for "SMS only", home network (applicable only when indicates E-UTRAN)"

" 2 UTRAN"

(based on http://m2msupport.net/m2msupport/atcreg-network-registration/ )

Could a better error message (like "no proper network") or something be given in the log, as this made me wonder if the hardware was broken, if the sim card was broekn or someone was doing something weird.

I would have understood "sms only" or something, but the error did make me wonder if the hardware had a issue, and/or the simcard.

Modem is a Sierra Wireless EM7455 Qualcomm Snapdragon X7 LTE-A, if that matter.

Comment 1 Aleksander Morgado 2018-06-06 12:36:50 UTC

Hey! Support for those kind of EPS related status responses is already implemented in MM 1.8. I assume it's not easy to retry it, so won't ask you to try to reproduce it with MM 1.8... :) Let's set it as fixed in 1.8 for now.

Comment 2 Michael Scherer 2018-06-06 14:32:41 UTC

I am not 100% sure this is due to the tunnel, as I got the same message in the office, so maybe just someone cancelled my service (sim card from my employer).

And while I wondered if this was fixed in 1.8, it seems that this part of the code (mm_3gpp_parse_creg_response) didn't change since 2016. 

However, the last commit seems to be on that exact same status of sms only. I will first investigate if there is a issue and try to backport modemManager and see how it go.

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